I could not find this as already hinted, so I thought that maybe someone does not know about it and/or finds it "useful." Open up a Terminal window. It doesn't matter which shell you prefer; I use tcsh. Type in emacs and press Enter. Once it's loaded, press and release Escape, and then type x. At the bottom of the screen, you'll see M-x; type tetris and press Enter.

You're now playing Tetris within emacs. Use the arrow keys and space bar (to drop blocks) to play. When you are done, a highscore will be generated at /tmp. You can then exit emacs by pressing Control-X followed by Control-C.

[robg adds: I modified the above instructions to be a bit more detailed than as originally submitted. Also, if your $TERM is set to VT100 (in Terminal Preferences), you'll get a black and white version with 0's instead of the colored graphics version shown here. To see the colors, set $TERM to ansi.]

ed? My God, that thing is bloated as hell! I use cat as my editor. No fancy junk like going back and correcting your mistakes! I still remember when programmers were MEN, not little sissies whining for syntax highlighting in their editors. Punch cards, tape reels, and disk drives the size of washing machines... now those were the days....

yeah, talk about a bloated editor... emacs offers pong too (for 2 players). Just enter "M-x pong" (M-x again equals to escape-x). One player can use the arrow-keys, the other the numbers 4 and 6.
Have fun!

Another way to jump straight into emacs' tetris mode is by starting up emacs the following way:

$ emacs -q --no-splash -f tetris

You could, if you wanted, create a shell alias like this in your .bash_profile file which would allow you to start it up very quickly by simply typing 'tetris':

alias tetris='emacs -q --no-splash -f tetris'

Oh, and selecting xterm-color instead of ansi for your terminal type in Terminal.app's preferences is more compatible. You'll experience fewer weird display problems that way, especially if you ever ssh or telnet to other systems.

I am a really beginner with Mac and Terminal. After I applied this hint in terminal, I have noticed that my Tetris did turn out to be the black and white version.

I know Rob mentioned that if $TERM is set to VT100 (in Terminal Preferences), it'll show up as B&W version. And if I like the color version, I have to set $TERM to ansi.

Maybe what rob said is very obvious to many advenced Mac users out there, but I have tried to change mine into color version without luck. Can somebody be kindly walkthrough the steps for me on how to change the $TERM to ansi? I'll be very very appreciated for your help!

---
Do not be arrogant because of your knowledge; Speak with those who know as well as those who do not - Ancient Egyptian Ptah Hotep

When I went to Terminal preferences, it just had two things- /bin/tcsh and open a saved .term . It had a select from file thing, but I don't know were to find it. sorry to be such a bother- im just a beginer